Water Heater Repair & Replacement

A standard 40 to 50 gallon replacement runs $2,100 to $2,800. Larger tanks cost more; see the next section for 70 to 75 gallon pricing.

Three things push the price up: where the heater is, how old the existing unit is, and how hard it is to get the old heater out and the new one in. Attic installs cost more because we have to hoist the old unit down and hoist the new one up.

A typical tankless install runs $2,000 to $5,000. Where it lands in that range depends on the application and what work the install needs.

Estimates on replacements and new installs are free.

A tank water heater lasts about 10 to 15 years. Most are older than their owners think. We regularly hear “we just put this in a couple of years ago,” and the manufacture date on the label says 9 years.

If your tank is already 9 years old, it's worth replacing it on your own schedule. That beats losing hot water at 6 on a Friday night, when nobody gets a hot shower that night or the next morning.

A tankless unit lasts 10 to 20 years, and maintenance decides which end of that range you get. The most common failure is a leak from the heat exchanger. The fix is tearing the unit down and rebuilding it around a new heat exchanger, which takes 3 to 6 hours and runs $800 to $2,000.

Whatever type you have, a water softener will help it last longer.

Check four things: the venting, the seismic straps, which side the expansion tank is on, and the sediment trap. These are the first things we look at on any water heater someone else installed.

Venting. We find dryer vent used on tank water heaters far too often. On a tankless unit the venting matters even more, because it's forced air. Venting that is wrong or not airtight can push carbon monoxide into your living space.

Seismic straps. Even clean-looking installs get these wrong: straps not joined properly in the middle, anchors in drywall instead of a stud, or drywall anchors. In an earthquake, a drywall screw won't hold a 400-pound water heater.

Expansion tank. It belongs on the cold side, not the hot side. Skipping it entirely stresses the whole plumbing system. After we installed a Moen leak detection device for one customer, he called the next day with a pressure reading of 170 PSI. The water heater had no thermal expansion tank.

Sediment trap. It protects the gas control valve, and many installers leave it out, which is a big reason those valves fail. When one is installed, the gas has to drop into the chamber first. We regularly see the tee laid so gas runs straight across, which defeats the purpose.

Every water heater we supply and install comes with a thermal expansion tank and a sediment trap. We walk through each of these checks in more detail in 4 signs your water heater was installed wrong.

Flush it once a year and replace the anode rod. Most homeowners never hear about either one. If your tank is already making noise, here is why a water heater pops or rumbles.

How you flush matters. We use a tool that pumps air into the tank while it flushes, so the sediment comes out with the water. A flush typically runs $125 to $250. If the tank is already rumbling loudly, the sediment may be too hard and clumped to clear, but we still recommend trying a flush before paying for a new heater.

Almost nobody replaces the anode rod, and a lot of plumbers install a heater, get paid, and leave without ever mentioning it.

Tankless units need their own care. At a minimum, put a sediment filter on the unit so sediment can't get in. We recommend a water softener on every tankless install, because hard water destroys these units.

Then descale it once a year by running a descaling solution through the unit. We're regularly called to tankless heaters acting up around year 5, and when we ask when they were last descaled, the owner has never heard of it.

Skipping the sediment trap or expansion tank to save money at install also shortens a heater's life, no matter how well you maintain it.